Winches with axially aligned, mechanically actuated brakes, and associated systems amd methods

Abstract

Winches with axially aligned, mechanically actuated brakes, and associated systems and methods are disclosed. A representative winch includes a cable drum rotatable in a winding direction and an unwinding direction, a drive motor, a drive shaft coupled to the drive motor and rotatable about a shaft axis, a gear train coupled to the drive shaft and the cable drum, and a mechanically actuated brake. The brake can include a first element coupled to the drive shaft and rotatable about the shaft axis, a second element coupled to the cable drum and rotatable about the shaft axis, and a friction element positioned between the first and second elements and rotatable about the shaft axis. At least one of the first and second elements can be movable toward and away from the other between an engaged position with the friction element clamped between the first and second elements, and a disengaged position with the friction element unclamped.

I/We claim: 
     
         1 . A winch, comprising
 a cable drum rotatable in a winding direction and an unwinding direction;   a drive motor;   a drive shaft coupled to the drive motor and rotatable about a shaft axis;   a gear train coupled to the drive shaft and the cable drum; and   a mechanically actuated brake having a first element coupled to the drive shaft and rotatable about the shaft axis, a second element coupled to the cable drum and rotatable about the shaft axis, and a friction element positioned between the first and second elements and rotatable about the shaft axis, wherein at least one of the first and second elements is movable toward and away from the other between an engaged position with the friction element clamped between the first and second elements, and a disengaged position with the friction element unclamped.   
     
     
         2 . The winch of  claim 1  wherein:
 the friction element includes a brake disc having at least one pawl notch; and
 wherein the winch further comprises: 
 
 at least one pawl that is pivotable relative to the brake disc and positioned to allow rotation of the brake disc in a first direction and prevent rotation of the brake disc in a second direction opposite the first direction. 
 
     
     
         3 . The winch of  claim 1 , further comprising a brake housing, and wherein:
 the gear train includes a sun gear;   the first element includes a brake grip positioned within the housing and slideably journaled to the sun gear to rotate with the sun gear and slide axially relative to the sun gear, the brake grip having internal threads;   the second element includes a brake driver positioned within the housing and connected to the drive shaft to rotate with the drive shaft, the brake driver having external threads threadably engaged with the internal threads of the brake grip; and   the friction element includes a brake disc positioned within the brake housing between the brake grip and the brake driver, the friction element further including a first disc pad facing toward the brake grip and a second disc pad facing toward the brake driver, the brake disc further having at least one pawl notch; and wherein the winch further comprises:   at least one pawl pivotably coupled to the brake housing and positioned to allow rotation of the brake disc in a first direction and prevent rotation of the brake disc in a second direction opposite the first direction.   
     
     
         4 . The winch of  claim 1  wherein the mechanically actuated brake is positioned external to the cable drum. 
     
     
         5 . The winch of  claim 1  wherein the gear train includes multiple planetary gear stages, and wherein the mechanically actuated brake is driven by at least one of the planetary stages. 
     
     
         6 . The winch of  claim 1  wherein the gear train includes a sun gear, and wherein the first element is slideably engaged with the sun gear, and wherein first element, the second element and the friction element are all axially removable from the winch along the shaft axis. 
     
     
         7 . The winch of  claim 6  wherein first element, the second element and the friction element form a subassembly and are all axially removable from the winch as a unit along the shaft axis. 
     
     
         8 . The winch of  claim 1  wherein the first and second elements are threadably engaged with each other. 
     
     
         9 . The winch of  claim 1  wherein the first and second elements are engaged with each other via corresponding cam surfaces. 
     
     
         10 . The winch of  claim 1  wherein at least one of the first and second elements is positioned to move toward and away from the other as a result of differences in rotational velocity between the first and second elements. 
     
     
         11 . A brake for a winch, the winch having a drive shaft rotatable about a drive shaft axis, the brake comprising:
 a first rotatable element positionable to align co-axially with the shaft axis;   a second rotatable element aligned co-axially with the first element;   a friction element positioned between, and aligned co-axially with, the first and second elements, wherein at least one of the first and second elements is movable toward and away from the other between an engaged position with the friction element clamped between the first and second elements, and a disengaged position with the friction element unclamped; and   a locking element positioned to allow rotation of the friction element in a first rotational direction and prevent rotation of the friction element in a second rotational direction opposite the first rotational direction.   
     
     
         12 . The brake of  claim 11 , further comprising a brake housing carrying the first rotatable element, the second rotatable element, the friction element, and the locking element. 
     
     
         13 . The brake of  claim 11  wherein the locking element includes a pawl that is pivotable relative to the friction element. 
     
     
         14 . The brake of  claim 11  wherein the winch includes a sun gear, and wherein the first rotatable element is slideably engagable with the sun gear. 
     
     
         15 . The brake of  claim 11  wherein the first and second elements are threadably engaged with each other. 
     
     
         16 . The brake of  claim 11  wherein the first and second elements are engaged with each other via corresponding cam surfaces. 
     
     
         17 . The brake of  claim 11  wherein at least one of the first and second elements is positioned to move toward and away from the other as a result of differences in rotational velocity between the first and second elements. 
     
     
         18 . A method for operating a winch, comprising:
 winding a winch cable onto a cable drum by driving a motor in a first rotational direction, the motor having a motor shaft and an engaged gear train coupled between the motor shaft and the cable drum;   unwinding the winch cable off the cable drum, while the gear train between the motor shaft and the cable drum is engaged, with the motor rotating in a second rotational direction opposite the first rotational direction; and   slowing or halting the winch cable from unwinding only when a rotational speed of a first element of a brake, coupled to the cable drum, exceeds a rotational speed of a second element of the brake, coupled to the motor shaft, causing the first and second elements to clamp a friction element therebetween while at least one of the first second elements is stopped from rotating, and while the first element, the second element and the friction element are aligned along a rotation axis of the motor shaft.   
     
     
         19 . The method of  claim 18 , further comprising operating a clutch to disengage the cable drum from the motor, and unwinding the winch cable off the cable drum without rotating the motor. 
     
     
         20 . The method of  claim 18  wherein at least one of the first and second elements threadably rotates toward the other to clamp the friction element. 
     
     
         21 . The method of  claim 18  wherein at least one of the first and second elements rotates a cam surface relative to the other to clamp the friction element. 
     
     
         22 . The method of  claim 18 , further comprising removing the first element, the second element, and the friction element, as a unit, from the winch.